The present invention relates to equipment for continuously separating foreign matter from unpurified liquid papermaking materials.
Unpurified liquid papermaking materials contain unnecessary things besides fibers. Recently in particular, such unnecessary things have become more and more diversified because papermaking materials have become richer in variety and utilization has been made of, for instance, wastepaper. There has been almost no equipment that can remove all this diversified foreign matter at one time. Previous efforts to cope with the diversification of foreign matter have included the separate use of two different types of equipment, one for removing light foreign matter and the other for removing heavy foreign matter. This has had the disadvantage that it involves great cost of equipment and needs a large space therefor. On the other hand, cyclone separators are limited in size because of their function. Therefore, several cyclone separators have been used at the same time if liquid papermaking materials are to be handled in quantity. Also in this case, the above-mentioned disadvantages have been inevitable. Furthermore, the cyclone separators have been arranged in a row and pipes for the supply of liquid papermaking materials, etc. have branched off to them, but the distances between the branch point and the cyclone separators have been different. Therefore, even if the cyclone separators are adjusted to the same operating conditions, they have not always performed uniform separating action and they have often given uneven purification. To obtain uniform purification, each cyclone separator has had to be adjusted individually. This adjustment has been very difficult to make, and it has been impossible to make it perfectly. As a result, it has been impossible to purify liquid papermaking materials satisfactorily.